What is the ruling on my refusal to attend my father's gathering after he expelled me, knowing that I have not completely severed ties with him?

It is obligatory for you to obey your father in returning to sit with him, and it is not permissible for you to refuse, because the father's right is great, and it is necessary to avoid harming him unless there is harm to the son in doing so. Righteousness towards parents and showing kindness to them are among the best deeds and the most beloved to Allah. For "The pleasure of the Lord is in the pleasure of the parent, and the displeasure of the Lord is in the displeasure of the parent," and "The parent is the middle gate of Paradise, so if you wish, you may lose this gate or preserve it."